1. Field of the Invention
The present invention relates to a chair, and more particularly, it relates to a chair having a height-controllable seat which is suitable for seating a baby thereon.
2. Description of the Background Art
A childcare chair for seating a baby preferably has a height-controllable seat. The nurser can face to the baby at a proper distance by controlling the height of the seat in response to the situation, thereby readily taking good care of the baby. When the seat is brought into a high position, the nurser can readily suckle or change the baby in a sitting or standing state. When the seat is brought into a low position, on the other hand, the nurser can readily suckle or change the baby while sitting directly on the floor, and the baby can be safely kept when it is fast asleep.
Such a height-controllable chair is described in Japanese Utility Model Laying-Open No. 4-32148 (1992), for example, This chair comprises a seat, a pair of first leg members and a pair of second leg members supporting the seat with respect to the floor face, first leg mounting members rotatably mounting upper end portions of the first leg members on the seat, second leg mounting members rotatably mounting upper end portions of the second leg members on the seat, and wheels which are rotatably mounted on lower end portions of the first and second leg members respectively to roll on the floor face. The first and second leg members are rotatably connected with each other at intermediate portions thereof respectively, while the first and second leg mounting members are held by the seat so that the distances therebetween are changeable.
In the chair having the aforementioned structure, it is possible to change the height of the seat in the following manner: The distances between the first and second leg mounting members are so changed as to change the cross angles between the first and second leg members. Thus, inclinations of the first and second leg members are changed respectively, thereby changing the height of the seat.
Due to the wheels which are mounted on the lower end portions of the leg members, it is possible to readily move the aforementioned chair to an arbitrary position while seating the baby. Due to the wheels, further, it is possible to readily move the first and leg members with respect to the floor face, whereby the height of the seat can be readily controlled.
Noting the function of the wheels facilitating the movement of the chair to an arbitrary position, the wheels are more preferably provided by casters, which can automatically turn wheels in response to change of the direction for moving the chair. Thus, it is possible to readily move the chair also along a winding path.
When casters are mounted on the lower end portions of the leg members forming the chair having the aforementioned structure, however, the chair encounters the following problem: Such casters comprise rotary yokes rotatably holding wheels, and these rotary yokes must be mounted to be rotatable about vertically directed axes, in order to allow turning of the wheels. Also when the casters are mounted on lower end portions of leg members forming a chair, the rotary yokes must be mounted on the leg members to be rotatable about vertically directed axes.
In the chair having the aforementioned structure, on the other hand, it is necessary to change the inclinations of the leg members, in order to change the height of the seat. When the inclinations of the leg members are thus changed, the rotation axes of the rotary yokes are disadvantageously displaced from the vertical direction although the same are correctly vertically directed when the leg members are at specific inclinations. Depending on the inclinations of the leg members, therefore, the rotary yokes are so hard to rotate that it is difficult to turn the wheels, leading to damage in function of the casters.